Identification device for surgical instrument

ABSTRACT

A device is provided for identifying certain characteristics of an end piece or end effector of a surgical instrument. A preferred embodiment provides a surgical stapling instrument having an electrical circuit contained on the stapling cartridge which is capable of indicating cartridge type and/or status (i.e., with or without staples) when a voltage or current is applied to the circuit.

This is a division of application Ser. No. 08/234,749, filed Apr. 28,1994, pending, which is hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a means for identifying certaincharacteristics of an end piece or end effector of a surgicalinstrument. One particular embodiment relates to the use of a means, fordetermining cartridge type and/or status, in an endoscopic cutting andstapling device.

BACKGROUND AND SUMMARY OF THE INVENTION

It is important for a surgeon to identify characteristics of instrumentswhich are being used in a surgical procedure in order to determinewhether the instruments are appropriate for their intended use.

Certain characteristics of the instrument may be obvious from viewingwhile others may not. For example, in an endoscopic surgical cutting andstapling instrument, whether an appropriate stapling cartridge is inplace in a stapling device, or whether staples have been fired, may notbe readily apparent from viewing the instrument. Also in the use ofinstruments having interchangeable end pieces for use with a commonhandle because the parts are interchangeable, specific replaceableinstrument characteristic may not be apparent from viewing the reusableinstrument handle. As the cost of producing and sterilizing instrumentsare taken into consideration, more disposable, replaceable instrumentparts are being used, particularly in endoscopic surgery. As a result,more frequently, surgeons are using instrument end pieces which may beinterchangeably attached to a reusable handle portion or the like.Particularly in endoscopic surgery, these instruments may present someinstrument characteristic identification difficulties because thesurgeon cannot see the instrument in a direct manner but is watching ona video display and manipulating the instrument based on what is seen inthe display.

Accordingly, the present invention provides a means for identifyingsurgical instrument characteristics. The identifying means may be usedto identify certain predetermined characteristics of an end piece of asurgical instrument. For example, an end piece of an instrument may havea shaft with an end effector on its distal end. The end effector andshaft may form a replaceable end piece which may be coupled or uncoupledfrom a handle. Alternatively, a portion of the end piece such as the endeffector itself or a portion of the end effector may be replaceable. Forexample, a stapling cartridge, may be removable and replaceable.

The end piece may have a variety of characteristics such as end effectortype or configuration, instrument length or size, or instrument status.The identifying means for determining end piece or end effectorcharacteristics designates the specific characteristics to the user orcontrol unit, for example, of an electromechanical powered instrument.Preferably the identifying means is integral with the end piece andpreferably is located in the end effector or the distal or operative endof the instrument.

A preferred embodiment incorporates the identification means in a linearcutting and stapling instrument. A linear cutting and staplinginstrument has end effector jaws which engage tissue and apply parallelrows of staples to secure and join layers of tissue while a cuttingmeans cuts between the rows of staples. A cartridge containing thestaples is located in an end effector at the distal end of the staplingdevice. Various types of cartridges may be used with the sameinstrument, depending on the particular application of the instrument.For example, depending on the predetermined tissue type or thickness,different cartridges may be used to vary the size of the gap between thetwo jaws of the end effector used to engage tissue for stapling.

It is important to know whether the appropriate cartridge for theparticular tissue or application is inserted in the end effector. Forexample, if a cartridge for thicker tissue is used in thin tissue, thedesired hemostasis might not occur and uncontrolled bleeding may resultwhen the tissue is cut. If a cartridge with a smaller gap is used infragile tissue such as lung tissue, the tissue may be torn orunnecessarily damaged.

It is also important to know whether the staples have already been firedfrom the cartridge or not so that the user does not inadvertently cuttissue without a means for providing hemostasis.

Therefore it is desirable to provide an identifying means for indicatingcartridge type and/or indicating whether the cartridge still containsstaples or has been fired.

Color coding to distinguish cartridge type has been used. Also, amechanical means for indicating cartridge status has been described.Mechanical lockout means have been described, for example, in U.S. Pat.Nos. 4,892,244 and 5,129,570. The mechanical lockout means mechanicallyprevent instrument refiring unless a single shot staple cartridge hasbeen replaced and the instrument reset. However, an electrical means fordetermining cartridge type or status has not been disclosed.

Accordingly, one aspect of the present invention provides a means,preferably electrical, for determining a cartridge type of a staplingdevice.

Another aspect of the invention provides a means for determiningcartridge status, i.e., whether staples are still present in thecartridge. Cartridge status may be determined by detecting whether ornot the instrument has been fired or how many times the instrument hasbeen fired.

If a one-shot staple cartridge is used, a detection means needs only todetermine whether or not the device has been fired with the existingcartridge in place. If a multifire staple is used, the detection meanscounts the number of times the device is fired.

The means for detecting instrument firing is preferably electrical asdescribed in the Detailed Description below. However, other means arecontemplated by this invention. For example a magnetic sensor may belocated on a stationary portion of the device. A driver for advancing acutting blade or firing staples may have a magnetic element whichadvances past and is detected by the sensor when the device is fired.If, for example, a multiple fire cartridge is used, the sensorcommunicates the firing to a control unit. The control unit contains alogic circuit which counts the number of times a device is fired. Othermeans for sensing cartridge firing may include, e.g., optical means. Thepresent invention also provides a means for preventing the use of theinstrument when a cartridge has been spent, i.e., when no staplesremain.

Preferably the present invention is incorporated into an instrumentusing electrical energy for other purposes, e.g., for cutting orcauterization or to provide electromechanical energy for instrumentpositioning and/or staple firing such as in an electromechanical cutter.

With increasing automation in surgery, it may be necessary for aninstrument control unit in an automated device to be capable ofrecognizing certain predetermined instrument characteristics. An exampleof such a device is an electromechanical cutting and stapling device inwhich a control unit sequences the steps of electromechanically assistedinstrument use. The control unit, or controller assists the stapling andcutting functions of the instrument by directing a suitable power meansto operate the business head or end effector of the instrument toconduct a desired step in the procedure. The power source sends anelectrical signal which is translated into electromechanical energypreferably either by or through a shaft. In preferred embodiments, theshaft is encased in a housing and a motion is provided to the shaft,i.e., rotation, longitudinal movement, etc. Means are disposed in theend effector to translate the motion of the shaft into a suitable forceand/or motion in the head to carry out a desired step, i.e., to set andform staples or to sever tissue, etc. Examples of electromechanicalcutters are described in U.S. Ser. Nos. 07/822,478, 07/991,619 and08/91,807 incorporated herein by reference. An improvedelectromechanical cutter would recognize, e.g., whether the staplecartridge is appropriate for the tissue thickness and type of tissue itis intended to cut and staple.

Thus, one embodiment of the present invention, provides a means fordetermining instrument characteristics in an electromechanical cutter. Apreferred embodiment provides an electromechanical device having acontrol unit for sequencing the steps of instrument use which alsoidentifies the instrument characteristics. An electromechanical cutteris preferred in which the control unit uses means to identify thecartridge type and determine whether the staples have been fired. If thecartridge is inappropriate or the staples have been fired, theninstrument use is locked out with a lock-out means. For example, thelock-out means may be contained in the logic of the control unit of anelectromechanically powered stapling device. The control unit will notcause the device to fire if the electrical means indicates aninappropriate or fired instrument status. In one embodiment where acutting device is used, the lock-out prevents advancing of the cuttingblade with an inappropriate or spent cartridge.

An alternative means for determining instrument characteristics providesoptical means for determining instrument characteristics. One embodimentprovides light emitted from a control unit and reflected by theinstrument. The light is sensed and converted into an electrical signal,e.g., using a photodiode associated with the control unit. The reflectedlight indicates a predetermined instrument characteristic for theparticular reflected light signal. For example a different cartridgetype would reflect light having a different intensity or wavelength.

Alternatively a discrete number of reflected light outputs eithertransmitting or blocking light, interface with a discrete number oflight sensors which sense the transmitted light. The resulting lightoutputs have an on or off status (reflecting or blocking) thusrepresenting a binary code preset to indicate specific end piececharacteristics. An advantage of the optical means is the shaft portionincluding the light input surface, light pipe, and output lenses arecapable of withstanding preferred radiation sterilization methods.

These and other objects of the invention will be better understood fromthe following Detailed Description of the Drawings and DetailedDescription of the Invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a linear cutting and stapling instrument;

FIG. 2 illustrates an exploded partial perspective of a cartridge holderand cartridge of a first embodiment of the invention;

FIG. 3 illustrates a front cross section of the cartridge holder andcartridge of FIG. 2;

FIG. 4 illustrates a cross section along the lines 4--4 of FIG. 3;

FIG. 5 illustrates a partial top view of the cartridge of FIG. 2;

FIG. 6 illustrates a cross section along the lines 6--6 of FIG. 5;

FIG. 7 illustrates a partial perspective view of an alternativecartridge of the present invention;

FIG. 8 illustrates a partial top view of the cartridge of FIG. 7;

FIG. 9 illustrates a front cross section of a cartridge holder andcartridge of another of the invention;

FIG. 10 illustrates a cross section of FIG. 9 along the lines 10--10;

FIG. 11 illustrates a top partial view of the cartridge of FIG. 9;

FIG. 12 illustrates a cross section of FIG. 11 along the lines 12--12;

FIG. 13 illustrates a circuit diagram of a circuit integral with acartridge of a third embodiment of the invention;

FIG. 14 illustrates an alternative of the present invention in which aoptical means indicates specific instrument characteristics;

FIG. 15 is an enlarged view of the light outputs and sensors of anoptical indication means;

FIG. 16 illustrates a perspective view of a proximal end of aninstrument shaft including an alternative embodiment of optical means;

FIG. 17 illustrates a perspective view of a distal end of an alternativeembodiment of the instrument of FIG. 1 including an optical lockoutmeans;

FIG. 18 illustrates a side cross-sectional view of the instrument ofFIG. 16 along the lines 18--18; and

FIG. 19 illustrates a perspective view of an instrument having analterative optical lockout means included with cutting means.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a linear cutting and stapling device 10 having ahandle portion 17 coupled to a shaft 19 having an end effector 15 on itsdistal end. The end effector 15 has two jaws 11, 13 between which tissuemay be engaged for cutting and stapling. The top jaw 13 comprises ananvil 14 for receiving and forming staples. The lower jaw 11 comprises acartridge holder 16 and a cartridge 12 insertable into cartridge holder16. Operation of linear cutting and stapling instruments are known inthe art and are discussed, for example, in U.S. Pat. Nos. 4,608,981,4,633,874, and U.S. application Ser. No. 07/917,636 incorporated hereinby reference.

An electrical energy communication means comprises wires 18 which enterthe instrument 10 through the handle 16 and communicates with a circuitin lower jaw 11. Wires 18 are coupled to a control unit (not shown)including a generator which supplies energy to the circuit.

In FIGS. 2-6 there is illustrated a first embodiment of a linear cuttingand stapling device. The cartridge 12 is illustrated inserted into thecartridge holder 16 in FIG. 3. The cartridge 12 has an electricallyconductive ribbon 20, such as a metallic foil, positioned across a knifeslot 29 extending longitudinally through the cartridge 12. An electricalcircuit integral to the cartridge includes the conductive ribbon 20acting as a mechanically actuated fuse, and electrical contacts 21, 22on each side of the ribbon 20. Conductive strips 23, 24 are located oninner walls 32 of cartridge channel 16 and make electrical contact withcontacts 21, 22 respectively when cartridge 12 is inserted in channel16. Alternatively, conductive strips may also be located on outer wallor within cartridge channel. Conductive strips 23, 24 are coupled towires 18 through which electrical energy is provided to the circuit andare electrically isolated from the cartridge channel using appropriateinsulation.

If the cartridge 12 is inserted in the cartridge channel 16, the ribbon20 is in place, and electrical energy is applied to the circuit, anelectrical signal appears at the output indicating that the instrumentis ready to fire. When the instrument is fired, a knife moves forward,through the knife slot 29 to cut tissue engaged between jaws as staplesare being applied. The ribbon 20 is cut as the knife moves through theknife slot 29. When the ribbon 20 is cut, the circuit is opened. Thus,when electrical energy is applied, no signal appears across the circuit,thereby indicating that the knife has been moved through the knife slot,i.e., that the instrument has been fired.

FIGS. 7 and 8 illustrate an alternative cartridge 212 to be used inconjunction with the cartridge channel of FIGS. 2-4 and 6. The cartridge212 is inserted to fit within a cartridge channel as illustrated inFIGS. 2-6. The cartridge 212 includes contacts 221, 222 which are incontact with conductive strips 23, 24 of the cartridge channel 16 wheninserted into the channel 16 for use.

The cartridge 212 includes side walls 232 having grooves 232a. Thecartridge 212 also includes an electrically conductive tab 220 havingelectrically conductive ears 220a, 220b, biased laterally from eachother such that ears 220a, 220b, are slidable within grooves. The distalend of the grooves include contacts 221 and 222 having holes 21a, 22a.

The instrument includes cutting element 281, with a cutting blade 282located on its distal end which may be passed through knife slot 229.The use of such cutting elements is known in cutting and staplinginstruments in the art. Typically, such cutting element is coupled to anactuating element associated with a handle of an instrument. Suchdevices are described, for example, in U.S. Pat. No. 4,608,981 and4,633,874. The cutting element 281 also includes a notch 283 on itsunder side.

The tab 220 also includes a slot 225 through which the knife 281 maypass as the instrument is actuated. The slot 225 includes a catch 226which engages with the notch 283 of the knife. After the notch 283engages with catch 226, the knife continues to advance until the bladestroke is completed. As the knife or cutting element 281 is advanceddistally, the notch on the knife couples with the tab 220 and advancesthe tab 220 distally until the ears 220a, 220b contact contacts 221,222. The tab 220 thereby closes a circuit which includes conductivestrips 23 and 24 and contacts 221, 222. The circuit is initially openuntil the device is actuated. The closed circuit provides an electricalsignal indicating that the instrument has been fired. The tab 220 andnotch 283 on the knife 281 are arranged so that the circuit will closeat the end of the blade stroke. The tab 220 remains in place withconductive ears 220a, 220b engaged in holes 21a, 22b at contacts 221,222, when the knife is retracted. Thus, when the cartridge is spent thetab will remain in its advanced position.

In FIGS. 9-11 there is illustrated cartridge 41 and cartridge channel 42of another embodiment of a linear cutting and stapling device. Thecartridge 41 is comprised of a fuse 40 which is included in a circuitintegral with the cartridge 41 and cartridge channel 42. A current maybe applied to the circuit to measure a voltage across the circuit. Ofcourse the current applied to determine a voltage across the circuitmust not exceed the fuse's design limit so as not to blow the fuse andopen the circuit. The cartridge channel 42 has conductive strips 43, 44which are located on inside walls 45 of cartridge channel 42 and areelectrically isolated from the walls 45 with insulation. The fuse 40 isin electrical contact with conductive strips 43, 44 on each side of thefuse 40 respectively. The conductive strips 43, 44 are also inelectrical communication with an electrical energy source (not shown),which may deliver a current to the circuit. When the device is fired, acurrent is delivered to the circuit, synchronous with the cutting andstaple forming action. This current is sufficiently above the designlimits of the fuse to cause the circuit to break. Thus, when the devicehas been fired and the staples used, there will be no electriccontinuity of the circuit and a zero voltage will appear across thecircuit.

In FIG. 13 there is illustrated a circuit diagram of a third embodimentof a linear cutting and stapling device. In this device the electricalmeans serves a dual purpose of identifying the cartridge type andindicating whether the instrument has been fired.

The cartridge comprises a fuse 50 and an impedance element 52. In thisembodiment, the impedance element is in series with the fuse 50. Thefuse 50 has a known small resistance, R_(f) preferable about 0.2 ohms.The impedance element 52 may be a resistor if, for example, a DC currentis used, or a capacitor if an AC current is used. An inductor also maybe used with an AC current source in which case the inductor is arrangedin parallel with the fuse 50.

The impedance element 52 is preferable of a high resistance value R_(c)as compared to R_(f), or high impedance value Z_(c) as compared toZ_(f). Hence the voltage across the circuit, V_(c) is approximatelyequal to IRc or IZ_(c) respectively. A low current may be applied acrossthe impedance element 52 to determine its value without blowing thefuse. The value of the impedance element corresponds to the cartridgetype. The resistance value for R_(c) or impedance value for Z_(c) ispreset to correspond to a particular one of a number of differentcartridges types. The values of the impedances for the various cartridgetypes are carefully spaced so that the various cartridges can bedistinguished. For example, in one embodiment, the R_(c) values are 5,50, and 100 ohms for three different tissue thickness ranges. In thisparticular example the current is preferably about 1-10 mA.

The fuse will not blow when a known first current of I₁, is deliveredthrough the circuit. When I₁ is applied, the voltage across the circuitis measured. In the embodiment using DC current, the resistance R_(c) iscalculated from the known current and R_(f) values; and the measuredvoltage. In the embodiment using AC current, the impedance, Z_(c), ofthe impedance element may be determined from the magnitude and phaserelationships between the current, I₁ , through the circuit and thevoltage across the circuit.

An indicator means may be used to indicate to a user or a control unit,which cartridge is being used, for example, for thin, regular or thicktissue. The indicator means may be visual, in the form of an annunciatorlight on the instrument itself, or, in the preferred embodiment, via atext overlay on the video monitor the surgeon watches while performingthe procedure. If the cartridge is identified as an appropriatecartridge for the intended application, the instrument may bemanipulated to engage tissue to be cut and the instrument fired. As theinstrument is fired the staples are applied, the knife is advanced and acurrent I₂, sufficient to blow the fuse, is applied. Obviously, I₂ ishigher than I₁. In this particular example the current, I₂, is about 100mA. After the fuse has been blown, a zero voltage will appear across thecircuit when energy is applied, indicating a fired cartridge status.

Alternatively, the cartridge may comprise an impedance element whichacts as a fuse. The impedance element has a resistance or impedancepreselected depending on the cartridge type, which may be measured byapplying a current below the impedance element's design tolerance. Thisembodiment operates as the third embodiment described above except thatthe function of fuse and resistor or impedance element is combined intothe impedance element.

Alternatively, in the case of the moving knife cutting the conductivefoil, (FIGS. 2-6) the foil may be produced with a known impedance valuecorresponding to a particular cartridge type.

In an electromechanically controlled instrument, firing is prevented bythe internal logic of the control means unit. If an inappropriate valueof resistance or an open circuit is detected for the desirableapplication, the control means inhibits the firing of the instrument.The control means may be incorporated into the device or may be separateand external to the instrument.

An alternative embodiment is shown in FIGS. 14 and 15 in which anoptical means is provided for determining instrument characteristics. Ahandpiece 61 includes on its distal end, a light source such as an LED62, and a series of light sensors 63 such as photodiodes. In FIG. 14 asingle light output 67 and light sensor 63 is illustrated. In FIG. 15 aplurality of light outputs and light sensors is schematically shown. Adisposable shaft 64 is removably coupled to the distal end of thehandpiece 61. The shaft 64 includes an end effector (not shown) on itsdistal end and a light guide 65 on its proximal end. The light guide maybe constructed in various shapes depending on the desired lighttransmitting effect. In the embodiment illustrated in FIG. 14, the lightguide 65 comprises a tubular member having a first facet 66 and a secondfacet 67 and is constructed from a light transmitting material whichtransmits light of predetermined wavelengths, e.g., infrared light. Thefirst light facet 66 includes a first reflective surface 66a and thesecond light facet 67 includes a second reflective surface 67a. Thereflective surfaces 66a, 67a reflect the incident light in a desireddirection.

For transmission of broad bandwidths of light, the light guide may beconstructed of a material such as, for example, glass, polycarbonate orpolysulfone. The light guide may be designed to act as a filter tofilter out unwanted light. A narrow bandwidth of wavelengths of lightmay be used as well, to identify instrument characteristics.

The shaft 64 is coupled to the handpiece 61 so the first facet 66 iscapable of receiving light emitted from LED 62. Light passing throughthe guide 65, is reflected at right angles to the axis of the guide 65by reflective surfaces 66a and 67a. The reflection causes light to exitat a desired facet. The second facet 67 is in communication with thesensor(s) 63 so that a portion of light transmitted through the lightguide 65 may be received by the sensor(s) 63.

In FIG. 15, a series of light outputs 69 is associated with the secondfacet 67. A series of reflective surfaces 68 is associated with theseries of light outputs 69 such that each reflective surface 68 reflectsa portion of light traveling through the light guide towards acorresponding light output 69. Each of the light outputs 69 isassociated with a corresponding light sensor 63 so that the light output69 communicates light to the corresponding sensor 63. Each light output69 either transmits light or blocks light so that each outputcommunicates one of two signals to a corresponding sensor, i.e., eitherlight "on" or "off". The sensors 63 thus convert the light signals intoa binary coded electrical signal.

The possible number of variations of signals and thus kinds ofinstruments or instrument characteristics which can be recognized by theinstrument identification device is equal to 2^(n) where N is the numberof light sensors. The resulting electrical signal may be communicated toa microprocessor which may interpret the data and respond appropriately.Preferably the sensors, data base and microprocessor are associated witha reusable handle portion of an instrument and the light input,reflective surfaces, and outputs are associated with a disposableinstrument end piece.

An alternative embodiment of the optical identification means provides asensor or sensors which comprise a material having a predeterminedreflectivity, i.e., index of light refraction, transmission of aparticular light component, or has a specific light built into thedevice using variables such as shape and/or material, which correspondsto one or more characteristics of the shaft or end piece coupled to theshaft. The sensor detects the amount of light, i.e., the incidentoptical power, and emits an electrical signal which corresponds to thepredetermined device characteristics.

Another variation of an optical means for indicating devicecharacteristics is illustrated in FIG. 16. The optical means comprises alight source 72 associated with a handle portion 71 for emitting lightto an input surface 76 on a circular shaped interfacing shaft 73 of anend piece 74. The shaft 73 has a discrete number of output lenses 75which interface with a discrete number of light sensors 77 associatedwith a circular distal end of the handle portion 71 which interfaceswith the shaft. The input surface 76 is coupled to the output lenses 75by way of a light pipe or guide 78, such as an optic fiber. The outputlenses 75 individually either block light or reflect the light. Theability to block or reflect light is built into the shaft on the endpiece, for example, by using reflective surfaces molded into the lightpipe. The result is a binary codedlight output which is preselected todepend on specific end piece characteristics.

Another embodiment of the optical identification means of the presentinvention is illustrated in FIGS. 17 and 18 in use with the linearcutting and stapling instrument of FIG. 1. The optical means includes anoptical path and an optical path interruption means for physicallyinterrupting transmission of light through said optical path to indicatean instrument state.

A perspective view of the end effector of the linear cutting andstapling instrument of FIG. 1 is shown in FIG. 17. The cartridge 12inserted into jaw member 11 includes a knife channel 80 extendinglongitudinally through the center of the cartridge 12. A cutting means81 is slidable through the knife channel 80. The cartridge 12 alsoincludes a flag member 90 rotatably attached on each side of thecartridge 12 at the proximal end of the cartridge 12, and perpendicularto a plane defined by the knife channel 80. The flag member 90 includesa flag 91 having two positions, an up position and a down position. Theflag 91 in the up position is situated at least partially in the knifechannel 80.

The cutting means 81 includes a blade 82 with a notch 83. Before or asthe cutting means is actuated, the instrument applies longitudinalparallel rows of staples along either side of the cut line. As thecutting means 81 is extended distally through the knife channel 80, thecutting means 81 passes over the flag 91 in the up position. When thecutting means is retracted, the notch 83 engages the flag 91 rotating itfrom the up position to the down position.

Jaw member 11 further comprises a light guide 84 comprising two parts, atransmitting portion 85 and a return portion 86. The transmittingportion 85 is coupled at the proximal end of the instrument, to a lightsource, extends distally through the shaft 19 and has a reflectivesurface 859 on its distal end for bending light in a desired direction.The return portion 86 is coupled at the proximal end of the instrumentto a light sensing means, extends longitudinally through the shaft 19 ona side opposite the knife channel 80 of said jaw member 11 and has areflective surface on its distal end. The transmitting portion 85 isarranged to direct light towards the return portion 86 of the lightguide 84 so that light transmitted through the light guide 84 travelsthrough an optical path between the two portions 85, 86. The opticalpath is arranged just proximal of the flag mechanism 90. The flag 91 isdimensioned so that in the up position, it interrupts the optical path,blocking light from transmitting from the transmitting portion 85 to thereturn portion 86 of the light guide 84. In the other position, the flag19 permits transmission of light between the two portions 85,86 of thelight guide 84.

The light sensing means senses light transmitted through the returnportion 86 of the light guide 84. If the flag 91 is up, then light istransmitted and the light sensing means generates a signal indicatingthat the device has not been fired. If the flag 91 is down, then thelight is blocked and the sensing means generates a signal indicatingthat the device has been fired. The flag 19 is returned to its upposition when the spent cartridge is replaced with a new cartridgecontaining staples.

The flag 91 may be moved by a number of means in addition to asdescribed above. For example, as the cutting means 81 is advanced, or asa wedge or staple driver is advanced or retracted.

Referring now to FIG. 19 there is illustrated an alternative applicationof the optical instrument identification means of FIGS. 15 and 16. Theoptical identification means of this embodiment comprises dynamic codecontained on a moving disposable part of an instrument. In thisparticular embodiment, an alternative cutting means 181 is slidablethrough the knife channel 80. The cutting means 181 includes a cuttingblade 182 and a series of notches 183 which permit light to pass fromthe transmitting portion 85 to the return portion 86 of the light guide84 when a particular notch 182 is situated in the optical path betweenthe transmitting portion 85 and return portion 86. The series of notchesmay be arranged in a pattern of varying notch width which defines theinstrument characteristic code.

The light sensor receives a light signal, and correspondingly transmitsa signal which may be converted to a digital signal and/or interpretedby a microprocessor or CPU using means well known in the art. The signalmay include, for example, the number of notches, the frequency of thenotches, the length of the notches, and/or a number of differentcharacteristic codes having distinct patterns comprised of a series ofnotches. These signal may be used to indicate specific instrumentcharacteristics including instrument type as well as real timeinformation such as instrument position (e.g., cutting means location)or speed. The code may also include an end of stroke indicator. Thesignal may cause the microprocessor to indicate various characteristicsto a user, and/or to respond and control the instrument according to thefeedback received from the instrument embodied in the signal.

Other moveable parts of the device may be used for the opticalinterruption means as well.

Alternatively, the optical means may include reflective surfacesarranged on, for example, the flag of FIGS. 17 and 18, or the cuttingmeans illustrated in FIG. 19. The cutting means may have a series ofreflectors arranged in a pattern on the cutting means in place of thenotches. The reflectors reflect the light back towards a sensor or lightguide generally on the same side of the cutting means as the lighttransmission means.

Several variations of this invention have been described. One specificembodiment has been illustrated in a linear cutting and staplinginstrument having a cartridge for containing and dispensing staples.This invention has also been described in connection with surgicalinstruments having a variety of attachable, replaceable end pieces withdifferent functions which can be distinguished by the identificationsmeans. Of course it is anticipated by this invention that the shaft, endeffector or cartridge may contain staples or other fastening means ormay have different functional attributes. Accordingly it will beunderstood by those skilled in the art that various changes andmodifications may be made in the invention without departing from itsscope, which is defined by the following claims and their equivalents.Of course numerous applications and variations of this invention arepossible.

We claim:
 1. An surgical fastening instrument having an end effectorcomprising:first and second jaw members for engaging and fasteningtissue; said first jaw member comprising a removable cartridgecontaining surgical fastening means; and a cartridge channel, said endeffector having an electrical identification device for identifyingcartridge type, wherein said identification device comprises animpedance element having a measurable, predetermined electricalcharacteristic.
 2. The surgical fastening instrument of claim 1 whereinsaid identification device is contained in said first jaw member.
 3. Thesurgical fastening instrument of claim 2 wherein stapling and firingfunctions are assisted by an electromechanical control means.
 4. Thesurgical instrument of claim 3 further comprising a lockout means forpreventing instrument firing when an inappropriate cartridge conditionis indicated by said identification device.
 5. The surgical instrumentof claim 4 wherein said lockout means is controlled by internal logic ofthe control means.
 6. The surgical fastening instrument of claim 2further comprising indicating means for indicating to user aninappropriate cartridge condition.
 7. The surgical fastening instrumentof claim 1 wherein said impedance element has a predetermined electricalimpedance; and wherein said impedance corresponds to an instrumentcharacteristic.
 8. The surgical fastening instrument of claim 7 whereinsaid impedance element comprises a resistor.
 9. The surgical fasteninginstrument of claim 7 wherein said impedance element comprises acapacitor.
 10. The surgical fastening instrument of claim 7 wherein saidimpedance element comprises an inductor.
 11. The surgical fasteninginstrument of claim 10 further comprising a fuse in series with saidimpedance element, said fuse capable of being blown by a current appliedto said fuse when said instrument is fired.
 12. The surgical fasteninginstrument of claim 7 further comprising a fuse in series with saidimpedance element, said fuse capable of being blown by a current appliedto said fuse when said instrument is fired.
 13. The surgical fasteninginstrument of claim 7 wherein said impedance element is a fuse having apredetermined resistance.
 14. A removable cartridge for a surgicalstapling instrument comprising an electrical identification device foridentifying cartridge type wherein said identification device comprisesan impedance element having a measurable, predetermined electricalcharacteristic.
 15. The cartridge of claim 14 wherein said impedanceelement has a predetermined electrical impedance.
 16. The cartridge ofclaim 15 wherein said impedance element comprises a resistor.
 17. Thecartridge of claim 15 wherein said impedance element comprises acapacitor.
 18. The cartridge of claim 15 wherein said impedance elementcomprises a inductor.
 19. The cartridge of claim 18 further comprising afuse in series with said impedance element, said fuse capable of beingblown by a current applied to said fuse when said instrument is fired.20. The cartridge of claim 15 further comprising a fuse in series withsaid impedance element, said fuse capable of being blown by a currentapplied to said fuse when said instrument is fired.
 21. The cartridge ofclaim 15 wherein said impedance element is a fuse.
 22. The cartridge ofclaim 15 wherein said impedance element comprises a fuse.